(C++) Generate RSA Key and Sign a String

See more RSA Examples

Demonstrates how to generate a new RSA public/private key pair and use it to generate a signature for a string. The (binary) digital signature is returned as a hexidecimalized string.

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#include <CkRsa.h>

void ChilkatSample(void)
    {
    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkRsa rsa;

    // Generate a 2048-bit RSA key.
    bool success = rsa.GenerateKey(2048);

    // To return the signature in hex.
    rsa.put_EncodingMode("hex");

    const char *strData = "This is the string to be signed.";

    // Sign the SHA256 hash of the string.
    const char *hexSig = rsa.signStringENC(strData,"sha256");

    std::cout << hexSig << "\r\n";
    std::cout << rsa.lastErrorText() << "\r\n";

    // Now verify the signature:
    success = rsa.VerifyStringENC(strData,"sha256",hexSig);
    if (success == true) {
        std::cout << "Signature verified!" << "\r\n";
    }
    else {
        std::cout << rsa.lastErrorText() << "\r\n";
    }

    // Try it with an invalid signature:
    success = rsa.VerifyStringENC(strData,"sha256","not a valid sig");
    if (success == true) {
        std::cout << "Signature verified!" << "\r\n";
    }
    else {
        std::cout << rsa.lastErrorText() << "\r\n";
    }

    // Try it with invalid data:
    success = rsa.VerifyStringENC("Not the original data","sha256",hexSig);
    if (success == true) {
        std::cout << "Signature verified!" << "\r\n";
    }
    else {
        std::cout << rsa.lastErrorText() << "\r\n";
    }

    // Try it with the wrong hash algorithm:
    success = rsa.VerifyStringENC(strData,"sha-1",hexSig);
    if (success == true) {
        std::cout << "Signature verified!" << "\r\n";
    }
    else {
        std::cout << rsa.lastErrorText() << "\r\n";
    }
    }